JP7164962B2 - Cooling structure of bearing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling structure for a bearing device and, for example, to a main shaft of a machine tool and a cooling structure for a bearing device incorporated in the main shaft.

At present, the so-called motor built-in type, in which a driving motor is built into the device, is becoming more common in the spindle devices of machine tools. In a motor built-in type spindle device, compressed air is used to cool the bearings in order to suppress the temperature rise of the bearings due to the heat generated by the motor (for example, Patent Document 1). In the bearing device of Patent Document 1, the bearing is lubricated with grease, and compressed air is discharged from an air supply port provided in the outer ring spacer toward the inner ring spacer to dissipate the inner ring spacer and the bearings adjacent thereto. , main shaft, etc.

Some spindle devices of machine tools have an air purge function using compressed air in order to prevent intrusion of cleaning fluid, cutting fluid, chips generated during machining, etc. (for example, Patent Document 2). . In the spindle device of Patent Document 2, compressed air supplied from the outside to the inside of the housing is discharged to the outside through a path that bypasses the bearings, so that impurities contained in the compressed air are removed from the bearings. It prevents adhesion and leakage of grease applied to the bearing (Paragraph 0043).

When the compressed air supplied from a single air compressor is used for both bearing cooling and air purging, conventionally, as shown in FIG. was That is, the compressed air A1 for cooling the bearing passes through the bearing cooling path 40 provided in the housing 2 and is blown toward the inner ring spacer 16 from the air supply port 23 provided in the outer ring spacer 15. After cooling the spacer 16 and the rolling bearings 3 and 4 on both sides thereof, the cooling air is discharged outside through an exhaust groove 41 provided in the outer ring spacer 15 and an exhaust path 42 provided in the housing 2 . Compressed air A2 for air purging passes through an air purging path 43 provided in the front cover 14 of the housing 2 and flows into a gap 44 between the spindle 1 and the front cover 14. is discharged to the outer periphery of the tip of the

JP 2014-062619 A JP 2007-105850 A

Typically, one air compressor is used per machine tool. In that case, from the viewpoint of downsizing the machine tool and suppressing energy consumption, a small-capacity air compressor with suppressed surplus power is used. Therefore, compressed air must be used effectively without waste. However, if the compressed air that had been used to cool the bearings was exhausted as it was in the conventional way, a single air compressor would have to supply both the compressed air for cooling the bearings and for purging the air, and the capacity of the air compressor would increase. There is a possibility that it will become insufficient and not be sufficiently effective for both bearing cooling and air purging.

An object of the present invention is to make effective use of compressed air so that both cooling and air purging of rolling bearings can be effectively performed while reducing the amount of compressed air used. It is an object of the present invention to provide a cooling structure for a bearing device capable of

A cooling structure for a bearing device according to the present invention is such that an outer ring spacer and an inner ring spacer are respectively interposed adjacent to an outer ring and an inner ring of a rolling bearing, the outer ring and the outer ring spacer are installed in a housing, and the inner ring and the inner ring are provided. In a bearing device in which a spacer is fitted to a rotating shaft,
The inner peripheral surface of the outer ring spacer is provided with an air supply port for blowing compressed air for cooling toward the outer peripheral surface of the inner ring spacer, and a spacer space between the inner ring spacer and the outer ring spacer. An exhaust path for guiding the compressed air is provided on the outer periphery of the distal end of the rotary shaft, and the exhaust path passes through the interior of the housing.

According to this configuration, compressed air for cooling is blown toward the outer peripheral surface of the inner ring spacer from the air supply port provided in the outer ring spacer. Compressed air impinging on the inner ring spacer takes away heat from the inner ring spacer, thereby efficiently cooling the inner ring and rotating shaft of the adjacent rolling bearing. After cooling the rolling bearings and the like, the compressed air is discharged to the outer circumference of the tip of the rotary shaft through the exhaust path, blowing off the cleaning fluid, cutting fluid, chips, etc. present in the surrounding area. In this way, since the compressed air used for cooling the rolling bearings and the like is also used for air purging, only one compressed air supply system is required, and the overall consumption of compressed air can be suppressed. Therefore, even with a relatively small-capacity air compressor, it is possible to effectively perform both cooling of the rolling bearing and air purging.

By passing the exhaust path inside the housing, the exhaust path can be completed only with the housing. Therefore, no special rolling bearings need to be used.

In this invention, the exhaust path has an in-housing path portion provided inside the housing, and a communication path portion that communicates the spacer space and the in-housing path portion, and the communication path portion includes: , a groove provided in an axial end face of the outer ring spacer.
If the communication path portion is a groove provided in the axial end face of the outer ring spacer, the communication path portion can be easily machined.

The connecting path portion may be provided on both axial end faces of the outer ring spacer.
In this case, the compressed air in the spacer space is discharged from both ends of the outer ring spacer in the axial direction to the path inside the housing, so the uneven flow of compressed air in the spacer space is reduced, and the inner ring spacer is evenly distributed. can be cooled to

In this invention, the compressed air supplied from the air supply port to the axial end portions of the inner ring spacer overhangs the outer diameter side and flows into the bearing space between the inner ring and the outer ring in the rolling bearing. An obstacle wall may be provided to prevent the
Since the obstruction wall prevents the compressed air from flowing into the bearing space, the leakage of grease in the bearing space can be further suppressed.

In the present invention, the air supply port is provided so as to be inclined forward in the rotational direction of the rotating shaft, and is positioned so as to extend from an arbitrary straight line in the radial direction in a cross section perpendicular to the axial center of the outer ring spacer. may be offset in a direction orthogonal to
When the air supply port is inclined in this way, the compressed air blown out from the air supply port flows in the axial direction while swirling along the outer peripheral surface of the inner ring spacer. When the compressed air swirls, the compressed air stays in contact with the outer peripheral surface of the inner ring spacer longer than when it flows straight in the axial direction, so that the inner ring spacer can be cooled more efficiently. Therefore, the cooling effect is improved, and the amount of compressed air used can be suppressed.
Further, when the air supply port is slanted, when the compressed air blown out from the air supply port hits the outer peripheral surface of the inner ring spacer, the pressing force of the compressed air can be applied to the inner ring spacer, and the rotating shaft can be rotated. A driving action can be expected.

A cooling structure for a bearing device according to the present invention is such that an outer ring spacer and an inner ring spacer are respectively interposed adjacent to an outer ring and an inner ring of a rolling bearing, the outer ring and the outer ring spacer are installed in a housing, and the inner ring and the inner ring are provided. In a bearing device in which a spacer is fitted to a rotating shaft, an air supply port for blowing cooling compressed air toward the outer peripheral surface of the inner ring spacer is provided on the inner peripheral surface of the outer ring spacer, An exhaust path is provided for guiding the compressed air from the spacer space between the seat and the outer ring spacer to the outer periphery of the tip of the rotating shaft. By effectively utilizing , it is possible to effectively perform both cooling and air purging of the rolling bearing while suppressing the amount of compressed air used, and it is possible to configure without using a special rolling bearing.

1 is a cross-sectional view of a bearing device provided with a cooling structure according to one embodiment of the invention; FIG. FIG. 2 is a partially enlarged view of FIG. 1; FIG. 3 is a diagram showing a part of FIG. 2 taken out; (A) and (B) are both views showing a part of the outer ring spacer developed. 3 is a cross-sectional view taken along the VV plane of FIG. 2; FIG. FIG. 4 is a cross-sectional view of a different bearing device; 1 is a cross-sectional view of a conventional bearing device; FIG.

A cooling structure for a bearing device according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG.
FIG. 1 is a sectional view showing the entire bearing device. This bearing device is for a machine tool, and a tool or a chuck is attached to the tip side (left side in the drawing) of a spindle 1 which is a rotating shaft. A main shaft 1 is rotatably supported with respect to a housing 2 by rolling bearings 3, 4 and 5 at axially spaced front and rear ends, respectively.

The rolling bearings 3 and 4 that support the tip portion of the main shaft 1 are both angular ball bearings arranged in a back-to-back arrangement. Another rolling bearing that supports the tip portion of the main shaft 1 may be provided at a position closer to the rear end than the rolling bearings 3 and 4 . A rolling bearing 5 supporting the rear end portion of the main shaft 1 is a cylindrical roller bearing and is used alone.

This bearing device for the main shaft is a so-called built-in motor drive system in which a motor is built inside the housing 2. Between the rolling bearings 3, 4 on the front end side and the rolling bearing 5 on the rear end side, 7 is provided. The built-in motor 7 is composed of a rotor 8 attached to the main shaft 1, a stator 9 attached to the housing 2, and the like. The rotor 8 is made up of permanent magnets and the like, and the stator 9 is made up of coils, cores and the like.

The housing 2 includes a housing main body 11, a rear housing member 12 disposed on the rear end side of the housing main body 11, and a cylindrical housing member 12 fitted to the inner periphery of the housing main body 11 at approximately the same axial position as the built-in motor 7. and a front cover 14 provided in contact with the front end surface of the housing body 11 . Outer rings 3 a and 4 a of the rolling bearings 3 and 4 are fitted to the inner periphery of the front end portion of the housing body 11 , and outer ring 5 a of the rolling bearing 5 is fitted to the inner periphery of the rear housing member 12 . The inner rings 3b, 4b, 5b of the rolling bearings 3, 4, 5 are fitted to the outer peripheral surface of the main shaft 1, respectively. Also, the stator 9 is attached to the inner circumference of the motor housing member 13 .

FIG. 2 shows the principal parts of a bearing device to which the cooling structure of the present invention is applied. 3 is a diagram showing a part of FIG. 2. FIG.
The rolling bearings 3, 4 supporting the tip portion of the main shaft 1 are angular contact ball bearings as described above, and a plurality of rolling elements 3c, 4c are interposed between the raceway surfaces of the outer rings 3a, 4a and the inner rings 3b, 4b. These rolling elements 3c and 4c are held by cages 3d and 4d at equal intervals in the circumferential direction. In this example, the pair of rolling bearings 3 and 4 are arranged in a back-to-back arrangement, but they may be arranged in a face-to-face arrangement.

In FIG. 3, the rolling bearing 3 has sealing members 3e and 3f attached to both axial ends of an outer ring 3a. Each seal member 3e, 3f is attached by fitting the outer diameter end into a circumferential groove provided in the outer ring 3a, and the seal lip of the inner diameter end is in contact with or close to the outer peripheral surface of the inner ring 3b. Grease is filled in the bearing space surrounded by the outer ring 3a, the inner ring 3b, and the sealing members 3e and 3f on both sides.

As with the rolling bearing 3, the rolling bearing 4 also has sealing members 4e and 4f attached to both ends of the outer ring 4a in the axial direction. Each seal member 4e, 4f is attached by fitting the outer diameter end into a circumferential groove provided in the outer ring 4a, and the seal lip of the inner diameter end is in contact with or close to the outer peripheral surface of the inner ring 4b. Grease is filled in the bearing space surrounded by the outer ring 4a, the inner ring 4b, and the sealing members 4e and 4f on both sides.

In FIG. 2, an outer ring spacer 15 and an inner ring spacer 16 are interposed between the pair of rolling bearings 3 and 4, respectively. The outer ring spacer 15 is fitted on the inner periphery of the housing body 11 , and the inner ring spacer 16 is fitted on the main shaft 1 .
The outer ring 3 a of the rolling bearing 3 is axially positioned by an outer ring spacer 15 and a front cover 14 . The outer ring 4 a of the rolling bearing 4 is axially positioned by the outer ring spacer 15 and the step surface 11 of the housing body 11 . The inner ring 3 b of the rolling bearing 3 is axially positioned by an inner ring spacer 16 and a front positioning spacer 17 . The front positioning spacer 17 is a rotating body arranged on the rear end side of the tip flange portion 1 a of the spindle 1 . The inner ring 4 b of the rolling bearing 4 is axially positioned by an inner ring spacer 16 and a rear positioning spacer 18 .

In FIG. 3, the outer ring spacer 15 has a convex cross-sectional shape including a cylindrical portion 15a and an annular convex portion 15b projecting radially inwardly from the axial center of the cylindrical portion 15a. On the other hand, the inner ring spacer 16 has a concave cross-sectional shape including a cylindrical portion 16a and a pair of obstacle walls 16b projecting radially outward from both axial ends of the cylindrical portion 16a. The inner peripheral surface of the annular convex portion 15b of the outer ring spacer 15 and the outer peripheral surface of the cylindrical portion 16a of the inner ring spacer 16 face each other with a radial gap 20 therebetween. Spacer spaces 21A and 21B are formed on both sides of the annular projection 15b in the axial direction so that the outer ring spacer 15 and the inner ring spacer 16 face each other with a certain distance therebetween.
In addition, in order to prevent the annular protrusion 15b of the outer ring spacer 15 from interfering with the obstacle wall 16b of the inner ring spacer 16 to prevent assembly, the inner ring spacer 16 is divided into two parts, for example, at an axially intermediate portion. .

In this example, the obstacle wall 16b of the inner ring spacer 16 has a shape that protrudes radially outward as it goes axially outward. Close to 3a and 4a. As a result, an axial gap 22 having a labyrinth effect is formed between the axially outer side surface of the obstacle wall 16b and the seal members 3e, 4e.

An air supply port 23 for blowing compressed cooling air A toward the outer peripheral surface of the cylindrical portion 16a of the inner ring spacer 16 is provided on the inner peripheral surface of the annular convex portion 15b of the outer ring spacer 15. As shown in FIG. In this example, as shown in FIG. 5, which is a cross-sectional view taken along line VV of FIG. 2, the number of air supply ports 23 is three, and the air supply ports 23 are evenly distributed in the circumferential direction.

The compressed air A is supplied from an air compressor (not shown) provided outside the bearing device. That is, as shown in FIG. 1, an air intake port 24 connected to the air compressor is open on the outer peripheral surface of the housing body 11, and an air supply path 25 leading to the air intake port 24 is formed inside the housing body 11. It is The air supply path 25 extends to the outer peripheral surface of the outer ring spacer 15 .

As shown in FIGS. 3 and 5, an introduction groove 26 for introducing compressed air A is provided on the outer peripheral surface of the outer ring spacer 15 . The introduction groove 26 is provided axially in the middle of the outer peripheral surface of the outer ring spacer 15 and communicates with the air supply ports 23 through the same number of connection holes 27 as the air supply ports 23 . The connection hole 27 is, for example, a hole extending in the radial direction. The air supply port 23 is a nozzle-like hole with a hole diameter smaller than that of the connection hole 27 .
Compressed air A taken in from an air intake port 24 (FIG. 1) passes through an air supply path 25, an introduction groove 26, and a connection hole 27 in order, and flows from the air supply port 23 to the outer circumference of the cylindrical portion 16a of the inner ring spacer 16. It is sprayed on the face.

As shown in FIG. 2, an exhaust path 30 is configured to guide the compressed air A from the spacer spaces 21A and 21B to the external space on the tip end side of the spindle 1. As shown in FIG. The exhaust path 30 is composed of a communication path portion 31 provided in the outer ring spacer 15 and an in-housing path portion 32 provided inside the housing 2 . Although the number of exhaust paths 30 is not particularly limited, for example, they are provided at three locations in the circumferential direction at equal intervals.

The communication path portion 31 is a radial groove provided on both axial end surfaces of the cylindrical portion 15 a of the outer ring spacer 15 . The connecting path portion 31 formed by this groove has, for example, a rectangular cross-sectional shape as shown in FIG. becomes. The position of the connecting path portion 31 in the circumferential direction may be the same as the air supply port 23 as shown in FIG. good.

In FIG. 2, the housing inner path portion 32 includes two radial portions 32a extending radially outward inside the housing body 11 following the connecting path portion 31, and connecting to the outer diameter ends of these radial portions 32a. and a bent portion 32c which is formed inside the front cover 14 and connects the front end of the axial portion 32b and the exhaust gap 33 . The exhaust gap 33 is an annular gap formed between the front cover 14 and the main shaft 1 and the front positioning spacer 17. The bent portion 32c is formed in the gap between the front cover 14 and the main shaft 1. The tip of the is open.

The rear end of the exhaust gap 33 is connected to the bearing space of the rolling bearing 3 on the front side. Therefore, when the pressure in the bearing space is high, the air in the bearing space flows through the exhaust gap 33 to the external space on the tip end side of the spindle 1 . However, since the cross-sectional shape of the exhaust gap 33 has a complicatedly bent labyrinth structure as a whole, foreign matter is suppressed from passing from the external space on the tip end side of the spindle 1 to the bearing space.

[Action of Cooling Structure of Bearing Device]
Compressed cooling air A is blown toward the outer peripheral surface of the cylindrical portion 16 a of the inner ring spacer 16 from an air supply port 23 provided in the outer ring spacer 15 during operation or the like. The compressed air A flows through the radial gap 20 into the spacer spaces 21A and 21B on both sides in the axial direction. During this time, the compressed air A removes heat from the inner ring spacer 16, thereby efficiently cooling the inner rings 3b, 4b of the rolling bearings 3, 4 and the main shaft 1 adjacent thereto.

After that, the compressed air A in the spacer spaces 21A and 21B passes through the exhaust path 30 and is discharged from the exhaust gap 33 to the external space on the tip end side of the spindle 1 . As a result, an air purging action for blowing away cleaning fluid, cutting fluid, chips, etc. present on the outer circumference of the tip flange portion 1a of the spindle 1 can be obtained.

By exhausting the compressed air A from the spacer spaces 21A and 21B through the exhaust path 30, the amount of the compressed air A passing through the bearing spaces of the rolling bearings 3 and 4 can be reduced. Therefore, leakage of grease in the bearing space is suppressed. In particular, in the case of this embodiment, since the obstacle walls 16b are provided at both ends of the inner ring spacer 16 in the axial direction, the compressed air A is prevented from flowing into the bearing space, and the grease in the bearing space leaks out. can be further suppressed.

As described above, the compressed air A used for cooling the inner ring spacer 16, the rolling bearings 3 and 4, etc. is also used for air purging, so the consumption of the compressed air A can be reduced. Therefore, even with a relatively small-capacity air compressor, it is possible to effectively perform both cooling and air purging of the inner ring spacer 16, rolling bearings 3 and 4, and the like. By passing the exhaust path 30 through the inside of the housing 2 , the exhaust path 30 can be completed only with the housing 2 . Therefore, special rolling bearings 3 and 4 do not have to be used.

[Other embodiments]
When the rotation direction of the main shaft 1 is constant, the connection hole 27 and the air supply port 23 may be inclined so that the inner diameter side is located forward in the rotation direction of the main shaft 1, as shown in FIG. In other words, the connection hole 27 and the air supply port 23 are offset from an arbitrary radial straight line L in the cross section perpendicular to the axial center of the outer ring spacer 15 in a direction perpendicular to the straight line L.

When the connection hole 27 and the air supply port 23 are inclined in this manner, the compressed air A blown out from the air supply port 23 flows along the outer peripheral surface of the inner ring spacer 16 while rotating in the axial direction. When the compressed air A swirls, the compressed air A stays in contact with the outer peripheral surface of the inner ring spacer 16 for a longer time than when it flows straight in the axial direction, so that the inner ring spacer 16 can be cooled more efficiently. can. Therefore, the cooling effect is improved, and the amount of compressed air A used can be suppressed.
Further, if the connecting hole 27 and the air supply port 23 are inclined, when the compressed air A blown out from the air supply port 23 hits the outer peripheral surface of the inner ring spacer 16, the pressing force of the compressed air A is reduced by the inner ring spacer. 16, and the effect of driving the spindle 1 can be expected.

In this embodiment, the rolling bearings 3 and 4 are lubricated with grease, but the cooling structure of the present invention can also be applied when the rolling bearings 3 and 4 are lubricated with oil such as air oil or oil mist. .

Although the embodiments for carrying out the present invention have been described above based on the embodiments, the embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

1... Main shaft (rotating shaft)
2 Housings 3, 4 Rolling bearings 3a, 4a Outer rings 3b, 4b Inner ring 15 Outer ring spacer 16 Inner ring spacer 16b Obstacle walls 21A, 21B Spacer space 23 Air supply port 30 Exhaust path 31 ... Communication path portion 32 ... In-housing path portion L ... Straight line A ... Compressed air

Claims (5)

An outer ring spacer and an inner ring spacer are respectively interposed adjacent to an outer ring and an inner ring of a rolling bearing that supports a spindle of a machine tool, the outer ring and the outer ring spacer are installed in a housing, the housing comprising a housing body, A bearing device having a front cover provided in contact with the front end surface of the housing body, wherein the inner ring and the inner ring spacer are fitted to the main shaft,
The inner peripheral surface of the outer ring spacer is provided with an air supply port for blowing compressed air for cooling toward the outer peripheral surface of the inner ring spacer, and a spacer space between the inner ring spacer and the outer ring spacer. An exhaust path for guiding the compressed air is provided to the outer periphery of the tip of the main shaft from
This exhaust path guides the compressed air exhausted from the spacer space through the inside of the housing to the gap between the front lid and the main shaft, and the front lid, the main shaft, and the front positioning spacer. and an annular exhaust gap formed between the rolling bearing, wherein the exhaust gap opens through a bent portion, and the rear end of the exhaust gap is connected to the bearing space of the rolling bearing. Equipment cooling structure. 2. The cooling structure for a bearing device according to claim 1, wherein the exhaust path comprises an in-housing path portion provided inside the housing and a communication path portion communicating between the spacer space and the in-housing path portion. and wherein the connecting path portion is a groove provided in the axial end face of the outer ring spacer. 3. The cooling structure for a bearing device according to claim 2, wherein said connecting path portion is provided on both axial end faces of said outer ring spacer. 4. The cooling structure for a bearing device according to any one of claims 1 to 3, wherein compressed air supplied from the air supply port protrudes radially outward from both ends of the inner ring spacer in the axial direction. A cooling structure for a bearing device, wherein a barrier wall is provided to prevent flow into a bearing space between the inner ring and the outer ring in the rolling bearing. 5. The cooling structure for a bearing device according to any one of claims 1 to 4, wherein the air supply port is provided so as to be inclined forward in the rotational direction of the main shaft. Cooling structure of a bearing device located at a position offset in a direction perpendicular to an arbitrary radial line in a cross section perpendicular to the axis.

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